JP3284593B2 - Stator coil of high voltage rotating electric machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator coil for a high-impedance rotary electric machine of a full impregnation type in which a stator coil is housed in a slot and then impregnated with a resin, and more particularly to an improvement in the structure of a surface corona prevention layer thereof.

[0002]

2. Description of the Related Art In a stator coil of a high-voltage rotating electric machine such as an induction motor or a generator, a resin impregnation method includes a method of impregnating a resin with a single stator coil and a method of accommodating a stator coil in an unimpregnated state in a slot. The method is further roughly classified into a total impregnation method in which coils are electrically connected to each other and then resin impregnation is performed. In particular, in the stator coil of the full impregnation method, the gap between the stator coil and the iron core slot is filled with a cured product of the impregnating resin, the iron core and the coil are integrated, and the heat conductivity between the coil and the iron core is high, and cooling is performed. It has excellent performance and has the advantage of simplifying the resin impregnation and heat-curing steps, and is widely used as an insulation method for small to large high-voltage rotating electric machines.

FIG. 6 is a cross-sectional view showing a main part of a stator coil of a conventional high-voltage rotating electric machine based on a full impregnation method. In the figure, a stator coil 1 has a plurality of insulated wire conductors inserted before inserting a rectangular parallelepiped coil side portion (called a slot portion) into a slot 9 radially formed in a stator core 10. A ground insulating layer 3 formed by tapering a predetermined number of mycates such as glass-based mica and film-based mica on the surface of the aligned coil conductor 2 wound or level-transferred. A semiconductive glass tape, a semiconductive film tape,
Alternatively, a base layer of the surface corona prevention layer 4 is formed by tapping a semiconductive tape such as a semiconductive nonwoven tape with a predetermined thickness. The non-impregnated stator coil (also referred to as a white coil) thus formed is housed in the slot 9 with the upper and lower two strips interposed between the coils with the inter-coil insulating material 5 interposed therebetween.
The opening of the slot is inserted into the wedge 8 through the insulating material 6 below the wedge.
After fixing the white coil to the stator core and making electrical connection between the coils, a resin impregnation process by a full impregnation method is performed.

[0004] In the resin impregnation process, the stator coil 10 in which the stator coil has been wound is housed in a vacuum impregnation layer and dried under vacuum.
Vacuum impregnation with a thermosetting impregnating resin such as epoxy resin at a predetermined temperature, and further impregnating the impregnation tank under pressure by pressing,
Thereafter, the stator coil 1 having the void-impregnated ground main insulating layer 3 is formed by transferring the resin from the impregnating tank to a curing tank at a predetermined temperature and curing the impregnated resin by heating, and preventing the resin-impregnated surface corona. The layer 4 is in conductive contact with the iron core 10 to maintain the potential of the surface corona prevention layer at substantially the same potential as that of the grounded stator core, and the inside of the slot 9 is formed by the cured product 7 of the impregnated resin impregnated in the gap with the iron core. The stator winding of the high-voltage rotating electric machine, which is coupled to the wall surface and in which the stator core 10 and the stator coil 1 are integrated, is formed.

[0005] The thus obtained stator winding by the full impregnation method has excellent thermal conductivity with the iron core, and can increase the current density of the aligned coil conductor 2 to reduce the size of the high-voltage rotating electric machine. In a rotating electrical machine having a high operating temperature and frequently starting and stopping, a thermal stress is generated between the integrated iron core 10 and the stator coil 1 due to a difference in thermal expansion coefficient therebetween. Peeling occurs at weak spots that cannot withstand stress. If this peeling position is on the interface between the inner wall surface of the slot 9 and the surface corona prevention layer 4, the surface corona prevention layer having semi-conductivity keeps conductive contact with the iron core in a portion other than the peeled portion, and prevents surface corona prevention. Since the potential of the layer is kept close to the potential of the grounded iron core, it is possible to avoid damage to the stator coil 1 due to generation of surface corona at the peeled portion. However, when peeling occurs between layers of the ground main insulating layer 3 or at the interface between the ground main insulating layer and the surface corona prevention layer due to thermal stress, a high voltage is generated at the peeled portion due to partial pressure of capacitance, which is caused by this. Discharge deterioration of the constituent material due to the internal partial discharge occurs, which causes a decrease in the insulation performance of the stator coil, and sometimes causes a problem that progresses to a situation in which the dielectric breakdown of the ground main insulating layer progresses.

In order to avoid such an unexpected situation,
As a base layer of the surface corona prevention layer 4, a taped layer formed by winding a conductive ethylene tetrafluoride tape is formed on the outer side of the ground insulating layer 3 so that the ethylene tetrafluoride hardens the impregnated resin. By using the peeling property of the surface to prevent the surface corona from being generated by causing peeling between the surface corona preventing layer 4 and the inner wall surface of the slot 9, heat acting between the stator coil and the iron core can be suppressed. A device configured to relieve stress is known (JP-A-56-83237).

Further, as a base layer of the surface corona prevention layer 4, a conductive tetrafluoroethylene tape whose surface on the side of the ground main insulating layer is subjected to surface treatment is used, and the main ground insulating layer 3 and the surface corona prevention layer are used. There is known a structure in which the peeling is hardly caused at the interface with No. 4 so that the internal partial discharge deterioration of the constituent material is more reliably prevented (Japanese Patent Application Laid-Open No. 58-179143).
No.).

[0008]

As a surface corona preventing layer, a conductive ethylene tetrafluoride tape or a conductive ethylene tetrafluoride tape having a surface on the side of the main insulating layer facing the ground is treated.
In the prior art using a pump, thermal stress is relaxed by causing separation between the surface corona prevention layer and the inner wall surface of the slot, and the occurrence of internal partial discharge and the discharge deterioration of the constituent material due to this are reduced. It becomes possible to suppress. However, since the conductive tetrafluoroethylene tape does not have the permeability of the impregnating resin, the conventional conductive tape using a semiconductive glass tape or a nonconductive nonwoven tape as the base layer of the surface corona preventing layer. As in the technique, it becomes difficult to supply the impregnated resin to the base layer of the main ground insulating layer through this base layer, and the ground main insulating layer 3 or the ground main insulating layer 3 which has been hardened and the surface corona prevention are prevented. Unimpregnated voids remain near the interface with the layer 4, and there is a problem that internal partial discharges and partial discharge deterioration of the constituent material due to the internal partial discharges occur in the voids.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stator coil having a surface corona preventing layer capable of relaxing thermal stress without impairing resin impregnating property, and thus having excellent cold / heat cycling resistance and generating no harmful partial discharge. is there.

[0010]

According to the present invention, there is provided, in accordance with the present invention, a main ground insulating layer covering a surface of an aligned coil conductor, a surface corona preventing layer formed outside the ground insulating layer, A semiconductive stress relaxation layer provided at a key point of the corona prevention layer to relieve a stress acting between the ground main insulation layer and the stator core, and inserted into a slot of the stator core to form a vacuum In a stator coil integrated with the iron core by a cured product of a thermosetting impregnating resin impregnated with pressure, a semiconductive layer in which a surface corona prevention layer is wound in two layers on the surface of a main insulating layer. It is composed of a tapered layer of a fiber tape and a composite semiconductive sheet interposed at a portion facing the side wall surface of the slot between the layers, and the composite semiconductive sheet is semiconductive. A semiconductive rubber layer, a semiconductive laminate on one side of the fiber base material And a semiconductive semi-cured resin layer provided with a semiconductive stress relieving layer. The surface corona preventing layer is formed so as to have semiconductive properties also in the thickness direction. Shall be.

[0011] Further, a main ground insulating layer covering the surface of the aligned coil conductor, a surface corona prevention layer formed outside the main insulating layer,
A semiconductive stress relaxation layer provided at a key point of the surface corona prevention layer to relieve stress acting between the ground main insulation layer and the stator core, and inserted into a slot of the stator core. In a stator coil integrated with the iron core by a cured product of a thermosetting impregnated resin impregnated with vacuum pressure, a composite semiconductive material in which a surface corona prevention layer is wound on the surface of a main insulating layer. This composite semiconductive tape is formed of a taped layer of tape, and the composite semiconductive tape is formed in close contact with a substrate made of a perforated plastic film which has been treated on one side with semiconductivity and on the surface on which semiconductivity has been treated on one side. A semi-conductive rubber layer, a semi-conductive laminating glass layer, or a semi-conductive semi-cured resin layer, and a composite material with a semi-conductive stress relieving layer. Main insulating layer with semiconductive stress relief layer outside Te on the surface - and those made by ping.

[0012]

In the structure of the present invention, a semiconductive stress relieving layer for relieving the stress acting between the main insulating layer to the ground and the stator core is provided with a full impregnation method to prevent the surface corona of the stator coil of the high-voltage rotating electric machine. A surface corona-preventing layer is provided at a key point of the layer, facing the tapering layer of the semiconductive fiber tape wound in two layers on the surface of the main insulating layer and the side wall surface of the slot between the layers. A composite semiconductive sheet interposed in a portion to be formed, and the composite semiconductive sheet is provided on one surface of the semiconductive fiber base material with a semiconductive rubber layer and a semiconductive laminate. A layer with a semiconductive stress-relaxation layer consisting of either a glass layer or a semiconductive semi-cured resin layer. By configuring the surface corona prevention layer to be semiconductive in its thickness direction The two semiconductive fiber tape layers of the surface corona prevention layer are insulated from the ground. Functioning as a resin impregnating passage to the ground, contributing to the formation of a void-impregnated ground-main insulating layer with few defects, and at the time of completion of the curing treatment, two layers of semiconductive fiber tape exert a binding force. Thus, the function of preventing the occurrence of peeling at the interface between the main insulating layer to the ground and the surface corona preventing layer can be obtained. Further, in the portion facing the side wall surface of the slot where the above-mentioned binding force is difficult to reach, the semiconductive stress relaxation layer interposed between the layers of the semiconductive fiber tape layer in this portion causes the thermal expansion of the coil and the iron core. Absorbs and relaxes the thermal stress caused by the difference and prevents peeling of the main insulation layer to the ground.
A function of preventing deterioration of the main insulating layer to ground due to internal partial discharge is obtained.

If the semiconductor stress relieving layer is made of a semiconductive rubber material or a semiconductive laminate glass material in which shrunk glass fibers are bonded with a conductive binder, the coefficient of thermal expansion is large and the rubber elasticity is high. Alternatively, a function of absorbing thermal stress is obtained by utilizing the property of the semiconductive stress relaxation layer which is rich in elasticity, and if a semiconductive semi-cured resin layer is used, the semiconductive semi-conductor which becomes brittle by thermosetting is obtained. Utilizing the properties of cured resin,
Thermal stress causes the semiconductive stress-relief layer to crack in the direction along the semi-conductive layer inside thereof, thereby relieving the stress and preventing the occurrence of peeling in the main insulating layer to the ground. In addition, it is short-circuited by the surface corona prevention layer having conductivity, and acts to prevent discharge from occurring in the crack.

Further, the surface corona preventing layer comprises a taped layer of a composite semiconductive tape wound on the surface of the main insulating layer. If a perforated plastic film that has been treated on one side with semiconductivity is used, the holes dispersed in the plastic film serve as impregnation passages, and a function of maintaining the voidless impregnation property of the main ground insulating layer can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a sectional view showing a stator coil of a high-voltage rotating electric machine according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a surface corona prevention layer portion in the embodiment. The duplicate description is omitted by attaching the reference numerals. In the figure, a stator coil 11 is a semiconductive polyester non-woven fabric wound in two layers on the surface of the main insulating layer 3 as a surface corona prevention layer 12 covering the outer side of the ground main insulating layer 3, A glass fiber tape 12 or a semiconductive fiber tape 12A, 12B, etc. 12 such as polyamide paper mixed with conductive fibers;
A composite semiconductive sheet 13 interposed at a portion facing the side wall surface of the slot 9 between the layers, the ground main insulating layer 3 and the surface corona are formed by a thermosetting impregnated resin impregnated by a full impregnation method. The prevention layer 14 is impregnated with a voidless material, and withstand voltage performance is given by a thermosetting treatment, and the stator coil 11 and the stator core 10 are joined together by the cured product 7 of the impregnated resin to be integrated, and have excellent heat conductivity. The stator of the high-voltage rotating electric machine provided with the stator windings is formed.

The composite semiconductive sheet 13 comprises the above-mentioned semiconductive fiber tape as a base material 13A and a semiconductive stress relaxation layer 13B formed on one surface thereof.
As the semiconductive stress relaxing layer 13B, a semiconductive rubber material of a silicone rubber type, a semiconductive laminate glass material formed by shrinking glass fiber into a sheet shape with a semiconductive binder,
Alternatively, any one of a semiconductive semi-cured resin layer in which graphite powder is blended with an epoxy resin containing a trace amount of a curing accelerator is used, and the surface corona prevention layer 14 is configured so as to have semi-conductivity also in its thickness direction. You.

In the stator coil 11 constructed as described above, the two semiconductive fiber tape layers 12 of the surface corona preventing layer 14 function as a resin impregnating passage to the main ground insulating layer 3, and are impregnated with a voidless material. In addition to contributing to the formation of the main insulation layer with few defects, the two-layer semiconductive fiber tape exerts a binding force at the time of completion of the curing treatment, and the main insulation layer and the surface corona prevention layer thereof. A function of preventing the occurrence of peeling at the interface with the substrate. Further, in a portion facing the side wall surface of the slot where the binding force is difficult to reach, the semiconductive stress relieving layer 13B interposed between the layers of the semiconductive fiber tape layer 12 in this portion forms the coil and the iron core. Absorbs and relaxes the thermal stress caused by the difference in thermal expansion and prevents separation of the main insulating layer to the ground, preventing deterioration of the main insulating layer to the ground due to internal partial discharge, and improving the resistance of the stator coil to cold / hot cycle. The function to do is obtained.

If the semiconductive stress relieving layer is made of a semiconductive rubber material or a semiconductive laminating glass material, a semiconductive stress material having a large coefficient of thermal expansion and having a high rubber elasticity or elasticity can be obtained. The function of absorbing thermal stress is obtained by utilizing the property of the relaxation layer.If a semiconductive semi-cured resin layer is used, the property of semi-conductive semi-cured resin that becomes brittle by heat curing The stress is relieved by the occurrence of cracks in the semiconductive stress relaxation layer in the layer direction in the interior thereof due to the stress, thereby preventing the occurrence of peeling in the main insulating layer to the ground and the cracks in the thickness direction around the periphery. Is also short-circuited by the conductive surface corona-preventing layer, thereby preventing discharge from occurring in the crack. Therefore, even if the obtained stator coil 11 is applied to a rotating electric machine which is excellent in insulation performance and resistance to cooling and heat cycling, has a high operating temperature and frequently starts and stops, it does not generate surface corona and internal partial discharge. A stator coil of a high-voltage rotating electric machine having excellent insulation reliability can be obtained.

FIG. 3 is a sectional view showing a stator coil of a high-voltage rotating electric machine according to another embodiment of the present invention, and FIG. 4 is an enlarged sectional view showing a surface corona prevention layer in another embodiment. In the figure, the surface corona prevention layer 24 is the main insulating layer 3
Is different from the above-described embodiment in that it is formed as a taping layer of a composite semiconductive tape 13 wound on the surface of the composite semiconductive tape 13. 13A is made of a perforated plastic film such as a polyester film or a polyimide film treated on one side with a semiconductive treatment, and a semiconductive rubber layer, a semiconductive laminate glass layer, or a semiconductive A semi-conductive resin layer 13B made of any of the semi-cured resin layers was supported, and the substrate 13A was wound with the base 13A facing the main insulating layer to form a surface corona prevention layer.

Therefore, if the composite semiconductive tape 13 is taped by a mechanized taping step to form the surface corona preventing layer 14, the entire surface of the coil is similar to that of the above-described embodiment. A stress relaxation function is obtained. Also, 2
By using a composite semiconductive tape having a layer structure, a function of relieving thermal stress near the interface with the slot can be obtained.

Further, the holes formed dispersed in the plastic film serve as impregnating passages to obtain the function of maintaining the voidless impregnation property of the main insulating layer to the ground, and to provide a semiconductive stress relief layer on the surface of the stator coil. Is formed to relieve thermal stress, thereby avoiding a decrease in resin impregnating property, which is a problem in the conventional technique using conductive tetrafluoroethylene tape, the operating temperature is high, and start-stop is frequently repeated. Even when applied to a rotating electric machine, it is possible to provide a stator coil of a high-voltage rotating electric machine which does not generate surface corona and internal partial discharge and has excellent insulation reliability. Further, this composite semiconductive tape is suitable for high-speed machine winding, and has the advantage that the taping step of the surface corona prevention layer can be saved and the thickness of the surface corona prevention layer can be reduced.

FIG. 5 is a characteristic diagram showing the change in the dielectric loss angle of the stator coil according to the embodiment due to the thermal cycle.
The horizontal axis represents the number of cooling / heating cycles with one temperature change from room temperature to 180 ° C. to room temperature, and the Δtan δ2 value is taken on the horizontal axis. In the drawing, the curve of Example 1 is a characteristic curve obtained with a model coil having a surface corona preventing layer having the structure shown in FIGS. 1 and 2, and the curve of Comparative Example is a conventional surface using a semiconductive fiber tape. The characteristic curve obtained with the model coil having the corona prevention layer is shown, and the thickness of the main ground insulating layer is set to a size corresponding to the stator coil of the high-voltage rotating electric machine having a rated voltage of 13.8 kv class. As is apparent from the figure, in the model coil including the semiconductive stress relaxation layer in the surface corona prevention layer according to Example 1, the Δtan δ2 value did not increase even after 3000 cycles of cooling and heating. The semi-conductive stress relaxation layer effectively suppresses the occurrence of peeling due to thermal stress at the interface between the main insulating layer to the ground or the main insulating layer to the surface and the surface corona prevention layer, and effectively suppresses the occurrence of internal partial discharge. It indicates that On the other hand, in the comparative example model coil, the Δtan δ2 value rapidly increased after 500 cycles of cooling and heating, and was caused by thermal stress at the surface main insulating layer or at the interface between the ground main insulating layer and the surface corona preventing layer. There is no function to suppress the occurrence of peeling, which indicates that intense internal partial discharge has occurred in this peeled portion,
The above experimental results clearly demonstrate the effect of improving the thermal cycling resistance by providing the semiconductive stress relaxation layer at the key points of the surface corona prevention layer.

[0023]

As described above, the present invention provides a stator coil for a high-voltage rotary electric machine by a full impregnation method, in which a semiconductive stress relaxation layer for relaxing the stress acting between the main insulating layer to the ground and the stator core is provided. The surface corona-preventing layer is provided with a semi-conductive fiber tape taped layer wound on the surface of the main insulating layer in two layers, and a slot between the layers. A composite semiconductive sheet interposed at a portion opposed to the side wall surface, and the composite semiconductive sheet is provided on one surface of the semiconductive fiber base material with a semiconductive rubber layer and a semiconductive rubber layer. It is provided with a semi-conductive stress relieving layer composed of either a conductive laminating glass layer or a semi-conductive semi-cured resin layer, and the surface corona prevention layer has a semi-conductive property in the thickness direction. With this configuration, the two semiconductive fiber tape layers of the surface corona prevention layer are grounded. It functions as a resin impregnating passage to the insulating layer, contributing to the formation of a void-impregnated ground insulating layer with few defects, and at the time of completion of the curing treatment, the two layers of semiconductive fiber tape exert a binding force. The function of exhibiting the function of preventing the occurrence of peeling at the interface with the ground main insulating layer and the surface corona prevention layer can be obtained. Further, in the portion facing the side wall surface of the slot where the above-mentioned binding force is difficult to reach, the semiconductive stress relaxation layer interposed between the layers of the semiconductive fiber tape layer in this portion causes the thermal expansion of the coil and the iron core. Absorbs and relaxes the thermal stress caused by the difference, and prevents separation of the main insulation layer to the ground.
A function of preventing deterioration of the main insulating layer to ground due to internal partial discharge is obtained.

Further, a semiconductive rubber layer, a semiconductive laminating
Combination of a semiconductive stress relieving layer composed of either a glass layer or a semiconductive semi-cured resin layer, and a substrate composed of a perforated plastic film such as a polyester film or polyimide film treated on one side with semiconductivity If a composite semiconductive tape is used, the base material of the surface corona prevention layer functions as a resin impregnating passage to the main ground insulating layer,
The conventional stator coil using conductive tetrafluoroethylene tape as the surface corona prevention layer prevents the resin impregnating property, which is a problem, and contributes to the formation of a void-impregnated ground insulating layer with few defects. And a composite semiconductive tape
Since the surface corona prevention layer with stress relaxation function can be easily formed by mechanically winding the coil outside the ground insulating layer, the stator coil of the high-voltage rotating electric machine with excellent cooling / heat cycle performance and insulation reliability can be economically manufactured. It can also be provided advantageously.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a stator coil of a high-voltage rotating electric machine according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a surface corona prevention layer portion in an example.

FIG. 3 is a sectional view showing a stator coil of a high-voltage rotating electric machine according to another embodiment of the present invention;

FIG. 4 is an enlarged cross-sectional view showing a surface corona prevention layer in different embodiments.

FIG. 5 is a characteristic diagram showing a change in a dielectric loss angle of the stator coil according to the embodiment due to a thermal cycle.

FIG. 6 is a cross-sectional view showing a main part of a stator coil of a conventional high-voltage rotating electric machine by an all-impregnation method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 stator coil 2 shaped coil conductor 3 ground insulating layer 4 surface corona prevention layer 7 cured product of impregnated resin 9 slot 10 stator core 11 stator coil 12 semiconductive fiber tape layer 13 composite semiconductive sheet G 13A semiconductive fiber base material 13B semiconductive stress relieving layer 14 surface corona prevention layer 24 surface corona prevention layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02K 3/30-3/52

Claims (2)

(57) [Claims] 1. A main insulating layer for ground covering a surface of an aligned coil conductor, a surface corona prevention layer formed on the outside thereof, and a main insulating layer for ground provided on important portions of the surface corona preventing layer and a stator. A semi-conductive stress-relaxing layer that relieves stress acting between the core and a core of a thermosetting impregnated resin impregnated with vacuum pressure after being inserted into a slot of the stator core. In the stator coil integrated with
A composite in which a surface corona-preventing layer is wound in two layers on the surface of the main insulating layer, and a semiconductive fiber tape taping layer is interposed at a portion facing a side wall surface of a slot between the layers. The composite semiconductive sheet comprises a semiconductive rubber layer, a semiconductive laminate glass layer, or a semiconductive sheet on one surface of a semiconductive fiber substrate. A semi-cured resin layer comprising a semi-conductive stress relaxation layer, wherein the surface corona prevention layer is formed so as to have semi-conductivity also in the thickness direction thereof. Electric motor stator coil. 2. A main insulating layer for ground covering the surface of the aligned coil conductor, a surface corona prevention layer formed on the outside thereof, and a main insulating layer provided on the surface of the main coil and a stator provided at important points of the surface corona preventing layer. A semiconductive stress-relaxing layer for relaxing stress acting between the core and a core of a thermosetting impregnated resin impregnated with vacuum pressure after being inserted into a slot of the stator core. In the stator coil integrated with
A perforated plastic film in which a surface corona prevention layer is formed of a composite semiconductive tape taped on the surface of a main insulating layer, and the composite semiconductive tape is treated on one side with semiconductive properties. A semi-conductive rubber layer, a semi-conductive laminate glass layer, or a semi-conductive semi-cured resin layer formed in close contact with one side of the semi-conductive treated surface. A high-pressure rotating member made of a composite material with a semiconductive stress relaxation layer, wherein the surface corona prevention layer is taped on the surface of the main insulating layer with the semiconductive stress relaxation layer outside. Electric motor stator coil.